Core Moisture

[Harryfl Arnold]

Our 45’ catamaran was diagnosed with an unacceptable amount of core (in our case: balsa) moisture through a water meter survey. We will need to be hauled for a complete survey and moisture mapping.

I found a company named Dry Boat (DRYBOAT® Structural Moisture Removal Services) whose method seems reasonable and cost effective. The BBB has no file. Any other input?

Other than cutting out the balsa, replacing the core, and replacing the fiber glass is there another restoration method to resolve this issue?

Harry Arnold
S/V Kuhela

[psk125]

Our boat was also diagnosed by a surveyor with an unacceptable amount of moisture in the balsa core. We were suspicious of this, however, because despite the extremely cold winter that included several warmer, well above-freezing days, there was no delamination anywhere in the hull. If things were as wet as we’d been told, ice in the core should have blown the laminates apart all over. A second surveyor put his moisture meter on the inside of the hull, where there was no paint, instead of on the outside. And it showed no moisture. Moisture meters are tricky tools. Thermal imaging is another, perhaps better, way to learn about moisture problems. On a boat, moisture gets everywhere and determining what constitutes a problem and what doesn’t can vary widely.

We did have issues with wet core in the cabin top, because of leaky fittings being mounted there. We cut open the underside of the cabin top in the saloon, (the overhead) so as to not have to re-do all the nonskid on the outside. That exposed rotted balsa, which we removed, wet balsa that was not well attached, which we also removed, and wet balsa that was still well-stuck, which we helped dry out with fans and lamps. We then replaced the balsa we had removed and re-glassed the overhead. Twenty years later it is still going strong.

[Fore and Aft]

I agree, moisture meters can be tricky to use and certainly divide opinions between surveyors. I like them and use them a fair bit but with the caveat that they are not perfect. A percussion test with a small hammer can also help determine if there is an issue. The thing with wet balsa core is you do not want to muck around as it can spread and cause even more damge.
Cheers

[boatpoker]

After in excess of 5,000 surveys I have a few thoughts on moisture meters and thermal imaging.

Moisture Meter Mythology and Flir thermal imager

[ozsailer]

Great stuff Boat Poker, always good to see someone who pass's on hard earning information to us plebs. It is greatly appreciated. Unfortunaley I once bought a boat that was listed as solid glass below the waterline, had it surveyed and was told it was solid as rock. Two years later we stripped the whole hull to remove the old core and re-glass. Hard lesson learned.




Greg H
Lagoon 440

[Harryfl Arnold]

Thanks guys... but
Is there another way to de-moisture balsa without cutting out the old? Is Dry Boat the only alternative?

[Chotu]

Originally Posted by Harryfl Arnold

Thanks guys... but
Is there another way to de-moisture balsa without cutting out the old? Is Dry Boat the only alternative?

This is an area where short cuts just don’t work. You have to cut the old core out. That’s the only way to get a real fix.